Some notable commentators have suggested that Donald Trump’s election to the presidency would fracture the Republican Party and spell the end of the GOP.

Whether those fears prove legitimate or overblown depends on what a President Trump did once in office.

But if a GOP dissolution came to pass, what would a post-Republican political landscape look like? Would Democrats run the country uncontested? Or would some new, stronger formation quickly arise?

Such a scenario has played out twice in American history, and each of those outcomes has prevailed.

We exist in what political scientists and historians call the Third Party System.

The First Party System pitted Federalists against Jeffersonian Democratic-Republicans. With George Washington nominally attached to the Federalists, that party held sway through the first decade after the Constitution replaced the Articles of Confederation.

But without Washington, and facing a rising popular sentiment for a more democratic government, the Federalists were doomed.

When Thomas Jefferson defeated John Adams in 1800, the Federalists were effectively run out of government. The First Party System limped on, Federalists maintained some state strongholds for a few more years and continued to have a small voice in Congress but they were done as a national force.

Then, divisions within the Jeffersonian ranks emerged, and those favoring a stronger national role in the economy -- as the Federalists had -- began poking their hands back up above ground.

Eventually, these National Republicans – men such as John Quincy Adams and Henry Clay -- would form the core of the Whig Party, a coalition that agreed on a few broad principles and were united in their hatred of the man who had by the late 1820s become the symbol of the emerging Democratic Party, Andrew Jackson.

Thus the Second Party System was born. For another two decades, the Democratic Party, organized by Martin Van Buren and dominated by Jackson, persevered. It did battle with big-government Whigs and usually won, in fights over a national bank, tariffs and westward expansion.

But there was one issue that could not be settled by politics alone.

Slavery would reshape the Democrats into a southern-dominated party while destroying the Whigs.

Many northern Democrats opposed to the expansion of slavery into the West abandoned their party. They were joined by anti-slavery Whigs and nativist Know Nothings in a new coalition that swept the congressional elections of 1854-55. Out of this miasma of competing interests, the Republican Party, founded in 1854, became the strongest faction and nominated its first presidential candidate, famed explorer John C. Fremont, in 1856.

Fremont lost to Democrat James Buchanan, but the system that emerged from that contest – Democrats v. Republicans – has been with us since.

Trumpism – whatever that is – does not pose the threat to national unity that slavery did, nor does it portend the destruction of an entire political movement.

But a President Trump acting more like the pre-2016 liberal populist he was than the rhetorically conservative populist he is today would put most Republicans in an impossible situation. They would have to abandon their president or risk losing what makes the Republican Party a going concern.

Much would depend on what kind of “deals” the self-described dealmaker strikes.

Even more would depend on how the millions of ordinary citizens who flocked to Trump’s promises -- to build a wall on the southern border and make Mexico pay for it, to impose high tariffs on trading partners or to block Muslims from entering the United States -- react when none of these things come to pass.

What then?

The realignments of 1800 and the 1850s were sparked not by political failures, but by successes. Jefferson's success coalescing the post-Revolutionary generation around the idea of a small national government with states in the ascendancy secured his party’s dominance. Democrat Stephen A. Douglas’s success winning enactment of the Kansas-Nebraska Act was the straw that broke the Whigs' back and divided his own.

What ensued was confusion and angling for supremacy.

But what emerged was a new system that operated much like the old one, with players in different uniforms but still playing the same game.

A Trump presidency would not necessarily spell the end of the Republican Party. But if it did, the people who had called themselves Republicans would still be part of the body politic and would still need a party. The ideas of a less-intrusive government and of America leading in the world would still be salient.

So Republicans should stop worrying about the demise of their party and embrace change on their own terms.

The last time a major national party went belly-up, it took only two elections for a member of the new party – the Republican Party -- to become president, a job that members of the GOP would then hold for most of the next seven decades.

John Bicknell is executive editor of Watchdog.org, a former CQ Roll Call editor and author of “America 1844: Religious Fervor, Westward Expansion and the Presidential Election That Transformed the Nation.” He is writing a book about the 1856 presidential campaign.Related: